LONDON (AFP) - All England Club senior citizens Lleyton Hewitt and Tommy Haas thrived at a sweltering Wimbledon on Saturday to reach the last 16.

Hewitt, the 2002 champion, reached the fourth round for the sixth year in succession with a 7-5, 7-6 (7/3), 6-3 win over Germany's Philipp Petzschner and will tackle Czech Radek Stepanek for a place in the quarter-finals.

The 28-year-old Australian, steadily rebuilding his career after a lengthy lay-off following hip surgery, has yet to drop a set and showed why he is such a danger by putting out Argentine fifth seed Juan Martin Del Potro in the second round.

"It's not easy to reach the fourth round for a sixth year in a row, but a Grand Slam isn't won in the first three rounds," said Hewitt who thrived in the 30-degree temperatures.

"It's all about finding a way through the first week. The draw opens up and you never know what might happen."

Two-time runner-up Andy Roddick of the United States, the sixth seed, also made it through with a gritty 7-6 (7/2), 7-6 (7/2), 4-6, 6-3 win over close friend, Jurgen Melzer.

It was Roddick's ninth win in nine matches against the Austrian and he will now tackle Tomas Berdych of the Czech Republic for a place in the quarter-finals.

"Jurgen served really well. He's such a good player on grass, he comes forward, uses tricky slices so I'm lucky to be in the fourth round," said Roddick.

German veteran Tommy Haas demanded Wimbledon install floodlights and introduce final set tiebreakers after winning a marathon five-set third round clash over Marin Cilic.

The 31-year-old German beat the 11th seeded Croatian 7-5, 7-5, 1-6, 6-7 (3/7), 10-8 in a four and a half hour tie which had started on Friday afternoon but had been held over for bad light.

"I don't know why they don't have lights here. I have never stopped a match a 6-6 before in the final set. It's tough to come back but I'm happy to get through," said Haas.

"I think they should be like the US Open and have a tie-break in the final set. I could hardly get out of bed today, but the adrenaline took over."

Haas, who won the Halle grasscourt tournament on the eve of Wimbledon, will now face Russian 29th seed Igor Andreev who saw off Andreas Seppi of Italy 6-1, 7-6 (7/5), 4-6, 7-6 (7/5) in another match held over.

Haas did have two match points in the fourth set tie-break on Friday before 20-year-old Cilic had two match points of his own in the 12th game of the decider before play was halted.

After eight defeats in eight outings, Berdych, the Czech 20th seed, pulled off his first win over Russian 12th seed Nikolay Davydenko, strolling to a comfortable 6-2, 6-3, 6-2 triumph.

"If there are more tournaments on grass, it would be better for me. But the grass is just for one month in the year," said Berdych who made the quarter-finals in 2007.

"I like to play here. The courts are good for me."

Later Saturday, British third seed Andy Murray faces Serbian 30th seed Viktor Troicki as he continues his bid to become the first home men's champion since Fred Perry in 1936.

Stepanek, the 23rd seed, defeated Spain's David Ferrer, the 16th seed, 7-5, 7-5, 3-6, 4-6, 6-4 as he looks to improve on his quarter-final showing in 2006.